Regulated power supply unit

ABSTRACT

An improved power supply unit includes a DC power source having a positive terminal and a negative terminal, and a voltage regulating circuit that includes a plurality of elements coupled in series between the positive and negative terminals of the DC power source to regulate the power supply signals supplied thereto to effectively cancel ripple and noise in such power supply signals. In one embodiment, the series-coupled elements include at least one resistor and a transconductive element having a characteristic transconductance value of T. The at least one resistor provides a resistance substantially equal to 1/T. The transconductive element and the one resistor cooperate to suppress spurious voltage level variations produced by the DC power source. The transconductive element may be realized by a thermionic triode, field effect transistor or other suitable device. In an alternate embodiment, the series-coupled elements include at least one active device and a transconductive element which cooperate to suppress spurious voltage level variations produced by the DC power source.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates broadly to the regulation of powersupplied to an electrical circuit. More particularly, this inventionrelates to the regulation of power supplied to sensitive equipment suchas high fidelity audio components.

[0003] 2. State of the Art

[0004] A power supply that provides a well-regulated noise-free andripple-free voltage level is an essential part of sensitive equipment,such as high fidelity audio components (e.g., audio preamplifiers,digital-to-analog converters, amplifiers, etc). Typically, suchequipment employs a switched power supply device and a complex feedbackand control scheme to minimize variations in the voltage level producedby the power supply. However, such complex feedback and control schemesare difficult and expensive to design and manufacture. Furthermore, suchfeedback power supply schemes can be detrimental to the sound quality ofaudio components in which they are used.

[0005] Thus, there is a great need for an improved power supplymechanism that efficiently provides a well-regulated supply of powersuitable for use in sensitive equipment, such as high fidelity audiocomponents (e.g., audio preamplifiers, digital-to-analog converters,amplifiers, etc).

SUMMARY OF THE INVENTION

[0006] It is therefore an object of the invention to provide a mechanismthat provides a well-regulated noise-free supply of power that issuitable for sensitive equipment, such as high fidelity audiocomponents.

[0007] It is another object of the invention to provide a well-regulatedsupply of power that is easy and inexpensive to design and manufacture.

[0008] It is a further object of the invention to provide circuitry thatminimizes variations in the voltage level produced by a DC power source.

[0009] It is an additional object of the invention to provide a powersupply unit that minimizes variations in the voltage level produced bythe power supply unit.

[0010] It is still another object of the invention to provide an audiocomponent that includes a power supply unit that minimizes variations inthe voltage level produced by the power supply unit.

[0011] In accord with these objects, which will be discussed in detailbelow, a power supply unit includes a DC power source and a voltageregulating circuit. The voltage regulating circuit includes a pluralityof elements coupled in series between the positive and negativeterminals of the DC power source which cooperate to suppress spuriousvoltage level variations produced by the DC power source.

[0012] According to one embodiment of the present invention, the seriesof elements include at least one resistor (R₁) and a transconductiveelement having a characteristic transconductance value of T. Theresistor (R₁) provides a resistance substantially equal to 1/T. Thetransconductive element and the resistor (R₁) cooperate to suppressspurious voltage level variations produced by the DC power source. Avoltage reference, which is preferably coupled between the input node ofthe one resistor (R₁) and a control terminal of the transconductiveelement, sets the DC output voltage and DC output current supplied to anactive load. In addition, the output impedance of the voltage regulatingcircuit is preferably made small (and approximates the resistance (1/T)of the resistor (R₁)) with the addition of at least one otherresistor(R₂) in the series-coupled chain of elements.

[0013] The transconductive element may be realized by a three-terminalthermionic triode, a three-terminal field effect transistor, a bipolartransistor, or other suitable device.

[0014] In another embodiment of the present invention, theseries-coupled chain of elements include at least one active device anda transconductive element. The at least one active device is operablycoupled between a first node and an output node. The transconductiveelement has an input terminal operably coupled to the first node. Theoutput node is operably coupled to the active load. The transconductiveelement operates in response to small signal voltage variations at thefirst node to provide a first small-signal voltage drop across thetransconductive element. The at least one active device provides asecond small-signal voltage drop between the first node and the outputnode that is substantially equal to the first small-signal voltage dropto thereby reduce variations in power supply signals provided by the DCpower source and supplied to the active load via the output node.

[0015] The transconductive element and the at least one active devicemay comprise vacuum tube devices (such as a matching triode valve deviceand diode valve device) or transistor devices (such as matching bipolartransistors) with substantially similar operating characteristics.

[0016] In accordance with the present invention, the improved powersupply unit is part of an audio component and is adapted to provide asupply of well-regulated power to the audio signal processing circuitryrealized therein.

[0017] Additional objects and advantages of the invention will becomeapparent to those skilled in the art upon reference to the detaileddescription taken in conjunction with the provided figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a schematic diagram of a generalized embodiment of animproved power supply unit in accordance with the present invention.

[0019]FIG. 2 is a schematic diagram of an exemplary embodiment of animproved power supply unit in accordance with the present invention,where a thermionic triode is used as the transconductive element thatprovides voltage regulation.

[0020]FIG. 3 is a schematic diagram of another exemplary embodiment ofan improved power supply unit in accordance with the present invention,where a field effect transistor is used as the transconductive elementthat provides voltage regulation.

[0021]FIG. 4A is a schematic diagram of an exemplary embodiment of animproved power supply unit in accordance with the present invention,wherein matching bipolar transistors are used as an active device andtransconductive element for voltage regulation.

[0022]FIG. 4B is a model of the improved power supply unit of FIG. 4Athat is used for AC signal analysis of the voltage regulation circuitrytherein.

[0023]FIG. 5 is a schematic diagram of an exemplary embodiment of animproved power supply unit in accordance with the present invention,wherein matching vacuum tube devices are used as an active device andtransconductive element for voltage regulation.

[0024]FIG. 6 is a pictorial illustration of an audio component (e.g.,audio preamplifier, digital-to-analog converter, amplifier, etc) thatutilizes an improved power supply unit to provide regulated voltage toaudio signal processing circuitry therein in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Turning now to FIG. 1, there is shown a generalized embodiment ofthe improved power supply unit 10 in accordance with the presentinvention, including a DC power source 12 having a positive inputterminal 14 and a negative input terminal 16. The DC power source 12 maybe an AC-to-DC power converter (which may be realized, for example, by amains transformer and associated components) that converts an AC powersignal from an AC power source (not shown) into the requisite DC voltagesignal. Alternatively, the DC power source 12 may be battery or othersuitable form of DC power supply. The DC power source 12 has its owncomplex internal impedance and noise associated with it. Part of theoperation of the power supply unit 10 is to nullify the effects ofthese.

[0026] A voltage regulation circuit 17 includes a number of circuitelements coupled in series between the positive and negative terminals14, 16 of the DC power source 12. These circuit elements include aresistor R2, resistor R1, and a transconductive element 18. Thetransconductive element 18 is a voltage-controlled current source thatproduces a current flowing therethrough (between terminals 1 and 3 asshown) in an amount proportional to a control voltage level suppliedthereto (which is supplied to control terminal 2 as shown). The ratio ofsuch current to the control voltage level is defined by a characteristictransconductance value T. Associated with any non-ideal transconductivedevice is a parallel resistance G as shown. The transconductive element18 may be a three terminal device, such as a thermionic triode 18 ashown in the embodiment of FIG. 2, a transistor 18 b shown in theembodiment of FIG. 3, or any similar device.

[0027] As shown in FIG. 1, node A is the junction of the positiveterminal 14 of the DC power source 12 and the resistor R2, node B is thejunction of resistor R2 and resistor R1, node C is the junction ofresistor R2 and the input of the transconductive element 18, and node Dis the junction of the output of element 18 and the negative terminal 16of the DC power source 12. Node D is the ground (or reference) for thepower supply unit 10, and node C provides a stabilized voltage level tothe active circuit load coupled thereto.

[0028] The voltage regulation circuit includes a voltage reference 20,preferably coupled between node B and the control terminal (e.g.,terminal 2) of the transconductive element 18 as shown, that supplies abias voltage level to the control terminal of the transconductiveelement 18. This bias voltage level along with the resistance value ofresistor R2 sets the DC operating characteristics of the transconductiveelement 18 and the steady state output voltage level and current levelsupplied to the active load from node C. Moreover, node B iselectrically coupled to the control terminal (e.g., terminal 2) of thetransconductive element 18 such that small signal variations in thevoltage level at node B are supplied to the control terminal. Thevoltage reference 20 may be realized by a zener diode, a gas glowdischarge tube or similar stable reference device.

[0029] For proper stabilization of the voltage level produced at theoutput node C, the resistance value of resistor R1 is substantiallyequal to 1/T. In this configuration, spurious fluctuations and noise atthe input node A are nulled out by compensation provided by the resistorR1 and the transconductive element 18. Such compensation is apparentfrom the following analysis of the circuitry.

[0030] One can assume that the current between node B and the controlterminal (e.g., terminal 2) of the transconductive element 18 isnegligible. In accordance with Kirchhoff's Current Law at node B, thecurrent flowing from node A to node B is equal to the current flowingnode B to node C, which provides: $\begin{matrix}{\frac{V_{a} - V_{b}}{R_{2}} = \frac{V_{b} - V_{c}}{R_{1}}} & (1)\end{matrix}$

[0031] Equation (1) can be rewritten as: $\begin{matrix}{V_{b} = {V_{c} + \left( {\left( {V_{a} - V_{c}} \right)\frac{R_{1}}{R_{1} + R_{2}}} \right)}} & (2)\end{matrix}$

[0032] Similarly, in accordance with Kirchhoff's Current Law at node C.,the current flowing from node A to node C is equal to the currentflowing node C to node D, which provides: $\begin{matrix}{\frac{V_{a} - V_{c}}{\left( {R_{1} + R_{2}} \right)} = {V_{b}T}} & (3)\end{matrix}$

[0033] Equation (3) can be rewritten as:

V _(c) =V _(a) −V _(b) T(R ₁ +R ₂)   (4)

[0034] Equation (2) can be plugged into equation (4) to yield thefollowing: $\begin{matrix}{V_{c} = {V_{a} - {{T\left( {R_{1} + R_{2}} \right)}\left( {V_{c} + \left( {\left( {V_{a} - V_{c}} \right)\frac{R_{1}}{R_{1} + R_{2}}} \right)} \right)}}} & (5)\end{matrix}$

 V _(c) =V _(a)−(TV _(c) R ₁ +TV _(c) R ₂ +TV _(a) R ₁ −TV _(c) R ₁)  (6)

_(t) V _(c) =V _(a) −TV _(c) R ₂ −TV _(a) R ₁   (7)

V _(c)(1+TR ₂)=V _(a)(1−TR ₁)   (8) $\begin{matrix}{V_{c} = {V_{a}\frac{\left( {1 - {TR}_{1}} \right)}{\left( {1 + {TR}_{2}} \right)}}} & (9)\end{matrix}$

[0035] If R₁=1/T, then V_(c)=0, which indicates that the voltagevariations in the power supply voltage at node A are substantiallysuppressed at the output node C.

[0036] Such operation can be explained as follows. Any spurious voltagevariations (Δv volts) at node B will cause a current I, which is equalto Δv *T amps, to flow through the transconductive element 18 due to itstransconductance T. This current I causes a voltage drop across resistorR₁ of I*R₁ which serves to substantially remove the effects of thevoltage variation Δv at the output node C. To illustrate this operation,consider the following example. Assume T has a value of 1 Amp/volt andR₁=1/T=1 ohm. If the spurious voltage variations (Δv) at node B is 1volt, then the current I (of Δv*T=1 amp) will flow through thetransconductive element 18. This will cause a voltage drop of I*R₁=1volt across the resistor R₁. Therefore, there is no change in thevoltage level at the output node C, and the spurious voltage variationpresent at node B is substantially removed from the output.

[0037] For sensitive active loads, such as high fidelity audiocomponents (e.g., audio preamplifiers, digital-to-analog converters,amplifiers, etc), it is desirable that the output impedance of thecircuit (as supplied to the active load) is small. The output impedanceof the circuit is the impedance caused by the transconductance(R₁+R₂)/(R₂*T) in parallel with the series impedance of resistors R₁ andR₂ (R₁+R₂) and in parallel with the characteristic resistance G of thetransconductive element 18. Initially, the resistance G can be neglectedto obtain the following expressions of the output resistance Z_(OUT) ofthe circuit: $\begin{matrix}{Z_{OUT} = \left( {\frac{R_{2}*T}{R_{1} + R_{2}} + \frac{1}{R_{1} + R_{2}}} \right)^{- 1}} & (10) \\{Z_{OUT} = \left( \frac{1 + \left( {R_{2}*T} \right)}{R_{1} + R_{2}} \right)^{- 1}} & (11) \\{Z_{OUT} = \left( \frac{R_{1} + R_{2}}{1 + \left( {R_{2}*T} \right)} \right)} & (12)\end{matrix}$

[0038] As described above, the value of resistance R₁ is selected suchthat it is substantially equal to 1/T, which can be plugged intoequation (12) to provide: $\begin{matrix}{Z_{OUT} = \left( \frac{R_{1} + R_{2}}{1 + \frac{R_{2}}{R_{1}}} \right)} & (13)\end{matrix}$

[0039] Multiplying equation (13) by resistance R₁ provides:$\begin{matrix}{Z_{OUT} = \left( \frac{R_{1}\left( {R_{1} + R_{2}} \right)}{R_{1} + R_{2}} \right)} & (14)\end{matrix}$

 Z _(OUT) =R ₁=(1/T)   (15)

[0040] Note that any current through the resistance G passes through aseparate branch of the network and does not alter the equations, yetmerely changes the output resistance Z_(OUT) to: $\begin{matrix}{Z_{OUT} = \left( {T + \frac{1}{G}} \right)^{- 1}} & (16)\end{matrix}$

[0041] This analysis shows that the impedance caused by thetransconductance tends toward (1/T) or R₁, and such impedance inparallel with (R₁+R₂) tends toward (1/T) or R₁. Thus, the outputimpedance of the circuit will approximate (1/T)=R₁ in parallel with G.If G is much larger than R₁, G may be neglected and the output impedanceof the circuit will approximate (1/T)=R₁, which can be small and thussuitable for sensitive active loads.

[0042] In addition, this analysis shows that the effect of variations inthe resistor R₂ (which may include any internal resistance or impedanceof the DC power supply 12) on such output resistance is cancelled out.

[0043] In alternate embodiments, such as those embodiments that utilizea FET-type transistor or a vacuum tube device as the transconductiveelement 18, the DC operating characteristics of the transconductiveelement 18 may be set by a reference voltage level provided to thecontrol terminal (e.g., terminal 2) of the transconductive element 18.This reference voltage level may be generated across one or moreresistors in response to a reference current supplied thereto by areference current source as is well known in the electronic arts.

[0044] Also note that the transconductance T of the transconductiveelement 18 will vary with the current passing through it. The additionof the resistance R₂ serves to minimize any effect such variation hasupon the noise-canceling and ripple-canceling performance at the outputnode C of the circuit. In addition, the resistor R₂ may be replaced byan active current source which supplies a constant DC current butpresents a high AC impedance as is well known in the electronic arts.This configuration can be modeled by setting the value of the resistorR₂ in the equations above to infinity. This modification will typicallyhave little effect while the circuit is in balance, but can potentiallyimprove the performance of the circuit when the value of resistance R₁is not precisely equal to (1/T).

[0045]FIG. 2 illustrates an exemplary embodiment of a power supply unit10 a that uses a thermionic triode 18 a as the transconductive elementin accordance with the present invention. In this exemplary embodiment,the power source 12 is a 400 volt power source. The thermionic triode 18a has a characteristic transconductance T of 10 mA/V and a parallelresistance G of 10 kOhms. Resistor R2 is 1150 ohms and resistor R1 is100 ohms. A voltage reference 20 of 262 volts is coupled between node Band the grid terminal of the triode 18 a to produce the DC operatingcharacteristics of 250 volts and 20 milliamps output from node C asshown. The resistance value of resistor R1 is substantially equal to 1/Tsuch that spurious voltage variations at node A are suppressed at theoutput node C. The resistor R₂ is large and the impedance G is muchlarger than R₁ such that the output impedance of the circuitapproximates (1/T)=R₁=100 ohms, which is suitable for sensitiveequipment.

[0046]FIG. 3 illustrates an exemplary embodiment of a power supply unit10 b that uses a field effect transistor 18 b as the transconductiveelement in accordance with the present invention. In this exemplaryembodiment, the power source 12 is a 40 volt power source. The fieldeffect transistor 18 b has a characteristic transconductance T of 1 A/Vand a parallel resistance G of 1 kOhms. Resistor R2 is 11.50 ohms andresistor R1 is 1 ohm. A voltage reference 20 of 26.2 volts is coupledbetween node B and the gate terminal of the field effect transistor toproduce the DC operating characteristics of 25 volts and 200 milliampsoutput from node C as shown. The resistance value of resistor R1 issubstantially equal to 1/T such that spurious voltage variations at nodeA are suppressed at the output node C. The resistor R₂ is large and theimpedance G is much larger than R₁ such that the output impedance of thecircuit approximates (1/T)=R₁=1 ohm, which is suitable for sensitiveequipment.

[0047] In an alternate embodiment of the present invention, theresistance R₁ of the voltage regulation circuits of FIGS. 1 through 3 asdescribed above may be replaced with an active device 19 that operatesin response to small-signal voltage variations at node B to provide asmall-signal voltage drop between nodes B and C that is substantiallyequal to the small-signal voltage drop between nodes B and D as providedby the transconductive element 18. The motivation for this design isevident from small-signal signal analysis of the circuits, which beginswith the application of Kirchhoff's Voltage Law at node C to provide:

v _(c) =v _(bd) −v _(bc)   (17)

[0048] where v_(bd) is the small-signal voltage drop between nodes B andD as provided by the transconductive element 18, and v_(bc) is thesmall-signal voltage drop between nodes B and C as provided by theactive device 19.

[0049] If v_(bd) is substantially equal to v_(bc), then v_(c) isapproximately zero, which indicates that the small-signal voltagevariations in the power supply voltage at node B (which are derived fromthe supply voltage variations at node A) are substantially suppressed atthe output node C, thus providing for improved noise and ripplecancellation at the output node C of the circuit.

[0050]FIG. 4A illustrates an exemplary embodiment that utilizes bipolartransistors (18 c and 19 a) for the transconductive element 18 and theactive device 19, respectively. Note that the bipolar transistor 19 a isdiode-connected such that the base and collector terminals of the deviceare tied to a common potential level at node B. In this configuration,it is important that the operating characteristics of the two bipolartransistors 18 c, 19 a substantially match one another in order toprovide for substantially equal small-signal voltage drops (e.g.,v_(bd)=v_(bc)) and thus effective cancellation of noise and ripple atthe output node C of the circuit. This constraint is evident from thesmall-signal analysis of a simplified model of the circuit as shown inFIG. 4B. In this simplified model, a hybrid-n transistor model is usedfor the bipolar transistors 18 c and 19 a, respectively.

[0051] Note that resistors r₀ ¹ and r₀ ² of the bipolar transistors 18 cand 19 a are typically large and can be ignored (e.g., replaced by anopen circuit). In addition, the currents flowing through r_(BE) ¹ andr_(BE) ² are typically much less than the current sources g_(m1)v₁ andg_(m2)v₂, respectively, and can be ignored. With these assumptions, onecan apply Kirchhoff's Current Law at node C to provide:

g _(m1) v ₁ =g _(m2) v ₂   (18)

[0052] In the event that the operating characteristics of the twobipolar transistors 18 c and 19a are matched, then g_(m1) issubstantially equally to g_(m2), and equation (18) can be simplified toprovide:

v₁=v₂   (19)

[0053] One can then apply Kirchhoff's Voltage Law at node C to provide:

v _(c) =v _(b) −v ₁   (20)

v _(c) =v ₂ −v ₁   (21)

[0054] Plugging in equation (19) into equation (21) yields:

v _(c) =v ₁ −v ₁=0   (22)

[0055] This analysis indicates that the small-signal voltage variationsin the power supply voltage at node B (which is derived from the voltagevariations at node A) are substantially suppressed at the output node C,thus providing for effective noise and ripple cancellation at the outputnode C of the circuit.

[0056]FIG. 5 illustrates an exemplary embodiment that utilizes vacuumtube devices (18 d and 19 b) for the transconductive element 18 and theactive device 19, respectively. Note that the vacuum tube device 18 d isa three terminal device (such as a triode valve) and the vacuum tubedevice 19 b is a two terminal device (such as a diode valve). In thisconfiguration, it is important that the operating characteristics of thetwo vacuum tube devices 18 c, 19 b substantially match one another inorder to provide for substantially equal small-signal voltage drops(e.g., v_(bd)=v_(bc)) and thus effective cancellation of noise andripple at the output node C of the circuit. This constraint may besatisfied by selecting a triode valve device 18 d whose transconductancechanges at the DC operating point with a slope that matches the slope ofthe change in the resistance of the diode valve device at the DCoperating point. Alternatively, matching triode valve devices may beselected, and one of the matching triode valve devices isdiode-connected to realize the active device 19 b, which is similar tothe exemplary embodiment described above with respect to FIGS. 4A and4B.

[0057]FIG. 6 illustrates an exemplary audio component 21 in accordancewith the present invention. The audio component 21 includes a DC powersource 12 enclosed within a system housing 22. The DC power source 12may be an AC-to-DC power converter (which may be realized, for example,by a mains transformer and associated components) that converts an ACpower signal from an AC power source (not shown) into the requisite DCvoltage signal. Alternatively, the DC power source 12 may be battery orother suitable form of DC power supply. At least one circuit board 24 isenclosed within the housing 22. The circuit board 24 includes a voltageregulation circuit 17 as described above with respect to FIGS. 1 through5B. The voltage regulation circuit 17 conditions the voltage levelsupplied by the DC power source 12 (by suppressing unwanted noise at itsoutput as described above) to provide a regulated voltage level to thepositive supply voltage strip (or node) 26 realized on the circuit board24. The DC power source 12 provides a reference voltage level (e.g.,ground) to the ground voltage supply strip (or node) 28 realized on thecircuit board 24. The positive voltage supply 26 and the negativevoltage supply 28 provide regulated power to audio signal processingcircuitry 30 realized on the circuit board 24. Such audio signalprocessing circuitry 30 may perform one or more of the followingfunctions: digital-to-analog conversion of audio signals;pre-amplification of analog audio signals for output to a low noiseamplifier; or amplification of analog audio signals for output to atleast one audio speaker.

[0058] There have been described and illustrated herein severalembodiments of an improved power supply unit that includes a simple andefficient voltage regulation circuit that compensates for spuriousvoltage level variations in the voltage levels supplied thereto. Whileparticular embodiments of the invention have been described, it is notintended that the invention be limited thereto, as it is intended thatthe invention be as broad in scope as the art will allow and that thespecification be read likewise. Thus, while particular voltage levels,current levels and other operating parameters have been disclosed, itwill be appreciated that other parameters are suitable as well. Inaddition, while particular types of three-terminal transconductiveelements have been disclosed, it will be understood othertransconductive elements can be used. Moreover, while particularconfigurations have been disclosed, it will be appreciated that otherconfigurations could be used as well. It will therefore be appreciatedby those skilled in the art that yet other modifications could be madeto the provided invention without deviating from its spirit and scope asclaimed.

What is claimed is:
 1. A power supply regulating circuit operablycoupled between a DC power source and an active load, the DC powersource including a positive terminal and a negative terminal, the powersupply regulating circuit comprising: a plurality of elements coupled inseries between said positive and negative terminals of said powersource, said elements including at least one resistor and atransconductive element, said transconductive element having acharacteristic transconductance value of T, and said at least oneresistor providing a resistance substantially equal to 1/T.
 2. A powersupply regulating circuit according to claim 1, wherein: saidtransconductive element comprises a three terminal device, wherein avoltage level is supplied to a first terminal and current flows betweensecond and third terminals of an amount substantially equal to saidvoltage level times said characteristic transconductance value T.
 3. Apower supply regulating circuit according to claim 2, wherein: said atleast one resistor comprises a first node and a second node, said firstnode being operably coupled to said first terminal of saidtransconductive element, and said second node being operably coupled tosaid second terminal of said transconductive element and said activeload.
 4. A power supply regulating circuit according to claim 3, furthercomprising: a voltage reference operably coupled between said first nodeand said first terminal of said transconductive element, wherein saidvoltage reference sets DC operating conditions of said transconductiveelement to thereby set DC output voltage and DC output current suppliedto said active load.
 5. A power supply regulating circuit according toclaim 1, wherein: said series of elements includes a first resistor R1and a second resistor R2, wherein said first resistor R1 provides aresistance substantially equal to 1/T, and said second resistor R2provides a resistance that is greater than 1/T and thus greater thansaid resistance of said first resistor R1.
 6. A power supply regulatingcircuit according to claim 1, wherein: an output impedance of said powersupply regulating circuit is substantially equal to 1/T.
 7. A powersupply regulating circuit according to claim 2, wherein: saidtransconductive element comprises a thermionic triode.
 8. A power supplyregulating circuit according to claim 2, wherein: said transconductiveelement comprises a transistor.
 9. A power supply regulating circuitaccording to claim 8, wherein: said transconductive element comprises afield effect transistor.
 10. A power supply regulating circuit accordingto claim 1, wherein: said active load comprises audio signal processingcircuitry.
 11. A power supply regulating circuit according to claim 10,wherein: said audio signal processing circuitry performs at least one of(i) digital-to-analog conversion of audio signals, (ii)pre-amplification of analog audio signals for output to a low noiseamplifier, and (iii) amplification of analog audio signals for output toat least one audio speaker.
 12. A power supply regulating circuitaccording to claim 1, wherein: said DC power source comprises anAC-to-DC power adapter.
 13. A power supply regulating circuit accordingto claim 1, wherein: said DC power source comprises a battery.
 14. Apower supply unit for supplying electrical power to an active load, thepower supply unit comprising: a DC power source including a positiveterminal and a negative terminal; and a plurality of elements coupled inseries between said positive and negative terminals of said powersource, said elements including at least one resistor and atransconductive element, said transconductive element having acharacteristic transconductance value of T, and said at least oneresistor providing a resistance substantially equal to 1/T.
 15. A powersupply unit according to claim 14, wherein: said transconductive elementcomprises a three terminal device, wherein a voltage level is suppliedto a first terminal and current flows between second and third terminalsof an amount substantially equal to said voltage level times saidcharacteristic transconductance value T.
 16. A power supply unitaccording to claim 15, wherein: said at least one resistor comprises afirst node and a second node, said first node being operably coupled tosaid first terminal of said transconductive element, and said secondnode being operably coupled to said second terminal of saidtransconductive element and said active load.
 17. A power supply unitaccording to claim 16, further comprising: a voltage reference operablycoupled between said first node and said first terminal of saidtransconductive element, wherein said voltage reference sets DCoperating conditions of said transconductive element to thereby set DCoutput voltage and DC output current supplied to said active load.
 18. Apower supply unit according to claim 14, wherein: said series ofelements includes a first resistor R1 and a second resistor R2, whereinsaid first resistor R1 provides a resistance substantially equal to 1/T,and said second resistor R2 provides a resistance that is greater than1/T and thus greater than said resistance of said first resistor R1. 19.A power supply unit according to claim 14, wherein: output impedance ofsaid power supply unit is substantially equal to 1/T.
 20. A power supplyunit according to claim 15, wherein: said transconductive elementcomprises a thermionic triode.
 21. A power supply unit according toclaim 15, wherein: said transconductive element comprises a transistor.22. A power supply unit according to claim 21, wherein: saidtransconductive element comprises a field effect transistor.
 23. A powersupply unit according to claim 14, wherein: said active load comprisesaudio signal processing circuitry.
 24. A power supply unit according toclaim 23, wherein: said audio signal processing circuitry performs atleast one of (i) digital-to-analog conversion of audio signals, (ii)pre-amplification of analog audio signals for output to a low noiseamplifier, and (iii) amplification of analog audio signals for output toat least one audio speaker.
 25. A power supply unit according to claim14, wherein: said DC power source comprises an AC-to-DC power adapter.26. A power supply unit according to claim 14, wherein: said DC powersource comprises a battery.
 27. An audio component comprising: a) audioprocessing circuitry; and b) a power supply unit for supplyingelectrical power to said audio processing circuitry, the power supplyunit including a DC power source including a positive terminal and anegative terminal, and a plurality of elements coupled in series betweensaid positive and negative terminals of said power source, said elementsincluding at least one resistor and a transconductive element, saidtransconductive element having a characteristic transconductance valueof T, and said at least one resistor providing a resistancesubstantially equal to 1/T.
 28. An audio component according to claim27, wherein: said transconductive element comprises a three terminaldevice, wherein a voltage level is supplied to a first terminal andcurrent flows between second and third terminals of an amountsubstantially equal to said voltage level times said characteristictransconductance value T.
 29. An audio component according to claim 28,wherein: said at least one resistor comprises a first node and a secondnode, said first node being operably coupled to said first terminal ofsaid transconductive element, and said second node being operablycoupled to said second terminal of said transconductive element and saidaudio processing circuitry.
 30. An audio component according to claim29, further comprising: a voltage reference operably coupled betweensaid first node and said first terminal of said transconductive element,wherein said voltage reference sets DC operating conditions of saidtransconductive element to thereby set DC output voltage and DC outputcurrent supplied to said active load.
 31. An audio component accordingto claim 27, wherein: said series of elements includes a first resistorR1 and a second resistor R2, wherein said first resistor R1 provides aresistance substantially equal to 1/T, and said second resistor R2provides a resistance that is greater than 1/T and thus greater thansaid resistance of said first resistor R1.
 32. An audio componentaccording to claim 28, wherein: said transconductive element comprises athermionic triode.
 33. An audio component according to claim 28,wherein: said transconductive element comprises a transistor.
 34. Anaudio component according to claim 33, wherein: said transconductiveelement comprises a field effect transistor.
 35. An audio componentaccording to claim 27, wherein: said audio signal processing circuitryperforms at least one of (i) digital-to-analog conversion of audiosignals, (ii) pre-amplification of analog audio signals for output to alow noise amplifier, and (iii) amplification of analog audio signals foroutput to at least one audio speaker.
 36. An audio component accordingto claim 27, wherein: said DC power source comprises an AC-to-DC poweradapter.
 37. An audio component according to claim 27, wherein: said DCpower source comprises a battery.
 38. A power supply regulating circuitoperably coupled between a DC power source and an active load, the DCpower source including a positive terminal and a negative terminal, thepower supply regulating circuit comprising: a plurality of elementscoupled in series between said positive and negative terminals of saidpower source, said elements including at least one active device and atransconductive element, said at least one active device operablycoupled between a first node and an output node, said transconductiveelement having an input terminal operably coupled to said first node,and said output node operably coupled to said active load, wherein saidtransconductive element operates in response to small signal voltagevariations at said first node to provide a first small-signal voltagedrop across said transconductive element, and wherein said at least oneactive device provides a second small-signal voltage drop between saidfirst node and said output node that is substantially equal to said-first small-signal voltage drop to thereby reduce variations in powersupply signals provided by said DC power source and supplied to saidactive load via said output node.
 39. A power supply regulating circuitaccording to claim 38, wherein: said transconductive element comprises athree terminal device, wherein a voltage level is supplied to a firstterminal and current flows between second and third terminals of anamount substantially equal to said voltage level times a characteristictransconductance value T.
 40. A power supply regulating circuitaccording to claim 39, further comprising: a voltage reference operablycoupled between said first node and said first terminal of saidtransconductive element, wherein said voltage reference sets DCoperating conditions of said transconductive element to thereby set DCoutput voltage and DC output current supplied to said active load.
 41. Apower supply regulating circuit according to claim 38, wherein: saidtransconductive element and said at least one active device comprisevacuum tube devices with substantially similar operatingcharacteristics.
 42. A power supply regulating circuit according toclaim 41, wherein: said transconductive element comprises a thermionictriode and said at least one active device comprises a vacuum tube diodedevice.
 43. A power supply regulating circuit according to claim 38,wherein: said transconductive element and said at least one activedevice comprise transistor devices with substantially similar operatingcharacteristics.
 44. A power supply regulating circuit according toclaim 43, wherein: said transconductive element and said at least oneactive device comprise matching bipolar transistors.
 45. A power supplyregulating circuit according to claim 38, wherein: said active loadcomprises audio signal processing circuitry.
 46. A power supplyregulating circuit according to claim 45, wherein: said audio signalprocessing circuit performs at least one of (i) digital-to-analogconversion of audio signals, (ii) pre-amplification of analog audiosignals for output to a low noise amplifier, and (iii) amplification ofanalog audio signals for output to at least one audio speaker.
 47. Apower supply regulating circuit according to claim 38, wherein: said DCpower source comprises an AC-to-DC power adapter.
 48. A power supplyregulating circuit according to claim 38, wherein: said DC power sourcecomprises a battery.
 49. A power supply unit for supplying electricalpower to an active load, the power supply unit comprising: a DC powersource including a positive terminal and a negative terminal; and aplurality of elements coupled in series between said positive andnegative terminals of said power source, said elements including atleast one active device and a transconductive element, said at least oneactive device operably coupled between a first node and an output node,said transconductive element having an input terminal operably coupledto said first node, and said output node operably coupled to said activeload, wherein said transconductive element operates in response to smallsignal voltage variations at said first node to provide a firstsmall-signal voltage drop across said transconductive element, andwherein said at least one active device provides a second small-signalvoltage drop between said first node and said output node that issubstantially equal to said first small-signal voltage drop to therebyreduce variations in power supply signals provided by said DC powersource and supplied to said active load via said output node.
 50. Apower supply unit according to claim 49, wherein: said transconductiveelement comprises a three terminal device, wherein a voltage level issupplied to a first terminal and current flows between second and thirdterminals of an amount substantially equal to said voltage level times acharacteristic transconductance value T.
 51. A power supply unitaccording to claim 50, further comprising: a voltage reference operablycoupled between said first node and said first terminal of saidtransconductive element, wherein said voltage reference sets DCoperating conditions of said transconductive element to thereby set DCoutput voltage and DC output current supplied to said active load.
 52. Apower supply unit according to claim 49, wherein: said transconductiveelement and said at least one active device comprise vacuum tube deviceswith substantially similar operating characteristics.
 53. A power supplyunit according to claim 52, wherein: said transconductive elementcomprises a thermionic triode and said at least one active devicecomprises a vacuum tube diode device.
 54. A power supply unit accordingto claim 49, wherein: said transconductive element and said at least oneactive device comprise transistor devices with substantially similaroperating characteristics.
 55. A power supply unit according to claim54, wherein: said transconductive element and said at least one activedevice comprise matching bipolar transistors.
 56. A power supply unitaccording to claim 49, wherein: said active load comprises audio signalprocessing circuitry.
 57. A power supply unit according to claim 56,wherein: said audio signal processing circuitry performs at least one(i) digital-to-analog conversion of audio signals, (ii)pre-amplification of analog audio signals for output to a low noiseamplifier, and (iii) amplification of analog audio signals for output toat least one audio speaker.
 58. A power supply unit according to claim49, wherein: said DC power source comprises an AC-to-DC power adapter.59. A power supply unit according to claim 49, wherein: said DC powersource comprises a battery.
 60. An audio component comprising: a) audiosignal processing circuitry; and b) a power supply unit for supplyingelectrical power to said audio signal processing circuitry, the powersupply unit including a DC power source including a positive terminaland a negative terminal, and a plurality of elements coupled in seriesbetween said positive and negative terminals of said power source, saidelements including at least one active device and a transconductiveelement, said at least one active device operably coupled between afirst node and an output node, said transconductive element having aninput terminal operably coupled to said first node, and said output nodeoperably coupled to said audio signal processing circuitry, wherein saidtransconductive element operates in response to small signal voltagevariations at said first node to provide a first small-signal voltagedrop across said transconductive element, and wherein said at least oneactive device provides a second small-signal voltage drop between saidfirst node and said output node that is substantially equal to saidfirst small-signal voltage drop to thereby reduce variations in powersupply signals provided by said DC power source and supplied to saidaudio signal processing circuitry via said output node.
 61. An audiocomponent according to claim 60, wherein: said transconductive elementcomprises a three terminal device, wherein a voltage level is suppliedto a first terminal and current flows between second and third terminalsof an amount substantially equal to said voltage level times acharacteristic transconductance value T.
 62. An audio componentaccording to claim 61, further comprising: a voltage reference operablycoupled between said first node and said first terminal of saidtransconductive element, wherein said voltage reference sets DCoperating conditions of said transconductive element to thereby set DCoutput voltage and DC output current supplied to said audio signalprocessing circuitry.
 63. An audio component according to claim 60,wherein: said transconductive element and said at least one activedevice comprise vacuum tube devices with substantially similar operatingcharacteristics.
 64. An audio component according to claim 63, wherein:said transconductive element comprises a thermionic triode and said atleast one active device comprises a vacuum tube diode device.
 65. Anaudio component according to claim 60, wherein: said transconductiveelement and said at least one active device comprise transistor deviceswith substantially similar operating characteristics.
 66. An audiocomponent according to claim 65, wherein: said transconductive elementand said at least one active device comprise matching bipolartransistors.
 67. An audio component according to claim 60, wherein: saidaudio signal processing circuitry performs at least one of (i)digital-to-analog conversion of audio signals, (ii) pre-amplification ofanalog audio signals for output to a low noise amplifier, and (iii)amplification of analog audio signals for output to at least one audiospeaker.
 68. An audio component according to claim 60, wherein: said DCpower source comprises an AC-to-DC power adapter.
 69. An audio componentaccording to claim 60, wherein: said DC power source comprises abattery.